| ObjectiveEstablishment of Sprague-Dawley rat model of chronic depression, through the dark avoidance test at different time of depression model rats learning and memory function, detection of nerve growth associated protein (neuronal growth associated protein, GAP-43) expression in hippocampus of rats with chronic depression model, to investigate the relationship between GAP-43 and learning and memory..Methods1. A correlation with learning and memory in 1 chronic depression rat model of Sprague-Dawley:healthy male SD 96 rats, were randomly divided intoohronic stress depression group, normal control group, depression group is divided into 21d,42d,60 d,3 sub groups, each group of matching the relative number of normal rats as control. The behaviors of all rats were observed, with dark experimental latency record each rats method (LT) and shuttling back and forth times (EN), to study the learning and spatial memory function.2. The relationship between the expression of learning and memory in rat hippocampal GAP-43 rat single cage feeding, dark avoidance test, noexternal stimuli were killed painless and chronic stress depression rats in blank control group, the rats in each group n=48 only. Chronic stressdepression group every subgroup dark avoidance test in 21d,42d,60 drats were sacrificed at different time points of painless, each time points in rats to detect the expression of GAP-43 n=16 only,. Take the half brainwere anesthetized rats in each group, the rapid hippocampal tissue was taken out, placed in a freezing tube, in liquid nitrogen after the move to -80 ℃ refrigerator to spare, the other half under ether anesthesia with 4% paraformaldehyde perfusion after whole brain radiotherapy in\ sucrosesolution were gradient overnight dehydration, application of OTC (Sakura, USA) embedding,-80 ℃ refrigerator for tissue sections. Specimens were examined by immunohistochemistry, the expression of RT-PCR and Western blot technology and method of chronic stress depression model rats hippocampal GAP-43mRNA and protein and explore the relationship between learning and spatial memory.Result:1. chronic stress depression rats after the success of rats with depression,detecting brain wave rats can collect a brain wave activity typical model.Model making success rate was 92.4%. The blank group dark avoidancetest results of LT was (56 ± 2.71s), EN (3.29 ± 1.14), depression model group:after the success of the 21d model (i.e., the successful model to twenty-first days) to avoid the dark trials of LT was (47.81 ± 3.31s), EN(2.76 ± 0.92); chronic depression the model group 42 days of dark avoidance test results for LT (38.51 ± 1.28s), EN (5.15 ± 1.21); chronic depression model group 60d avoid dark test results (46.73 ± 2.61s), EN (2.35 ± 1.01), chronic stress rat model of depression group and control group decreased significantly than learning memory capacity (P< 0.05).2. molecular biology detection:(1) immunohistochemical results:GAP-43 immunohistochemical staining results showed hippocampal cells into brown. The percentage of positive cells of chronic stress depression model group and blank control group were significantly different (P< 0.05), model group was significantly lower than that of the control group. The model group, the percentage of positive cells of 42d was obviously lower than that of 21 d group,60d group,42dgroup was the lowest (P< 0.05).(2) RT-PCR in the maker controls to strip is clearly visible, by measuring the optical density value of each band, and GADPH housekeeping gene ratio proofreading, chronic stress depression model group and blank control group were significantly different (P< 0.05), the model group was significantly lower than that of the control group.Compared with model group, the optical density value of 21d,60dproofreading lit group was significantly higher than that in 42d group,42dgroup was the lowest (P< 0.05).(3) Western blot blotting results:the expression of GAP-43 protein in hippocampus of rats in each group were compared in the standard proteinmolecular, reference maker, through the determination of the bjectiveoptical density with values, and β-actin housekeeping gene protein ratio proofreading, chronic stress depression model group and blank control group were significantly different(P< 0.05), the model group was significantly lower than that of the control group. Compared with model group, the optical density value of 21d,60d proofreading lit group was significantly higher 42d,42d group was the lowest (P< 0.05).Conclusion:1. chronic stress depression model rats were successfully established, electrophysi-ology detection and observation of rat brain by behavior,cognitive function of depression in the physiological effects of learning andspatial memory in rats.2. Chronic stress depression model rats at different time and spacelearning memory function, prove that chronic stress depression model ratslearning and memory impaired cognitive function. And further evidence ofchronic stress depression and hippocampus are closely related, the hippocampus plays a very important role in chronic stress depressionmodel rats. The learning and memory function of 3.GAP-43 may be involved in the chronic stress depression, is an important molecular basis of their learningand spatial memory. |
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